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United States Patent | 5,292,355 |
Nikander | March 8, 1994 |
The invention relates to a method and apparatus for bending a glass sheet. A glass sheet heated close to its softening temperature is supported on a ring mould and the glass sheet is allowed to bend by gravity. If necessary, the bending can be assisted mechanically. Air is circulated from a furnace section (1.1) above a glass sheet (7) to be bent into a furnace section (1.2) below the glass sheet so as to produce a different pressure effect on the opposite sides of a glass sheet (7). This pressure effect is used to support the glass sheet which is also heated over its central area to a sufficient temperature for bending and/or tempering, said temperature being sufficiently high that, without said support provided by the pressure effect, the central glass sheet area would bend and sag excessively downwards. The generation of pressure effect can be intensified by fitting the furnace with a ceiling (3) which includes an opening (3.1) for positioning said ring mould (6) together with its glass sheet (7) in alignment therewith.
Inventors: | Nikander; Risto K. (Kemiankatu 10, SF-33720 Tampere, FI) |
Appl. No.: | 956481 |
Filed: | December 31, 1992 |
PCT Filed: | June 12, 1991 |
PCT NO: | PCT/FI91/00187 |
371 Date: | December 31, 1992 |
102(e) Date: | December 31, 1992 |
PCT PUB.NO.: | WO92/00921 |
PCT PUB. Date: | January 23, 1992 |
Jul 05, 1990[FI] | 903397 |
Current U.S. Class: | 65/107; 65/25.4; 65/104; 65/182.2; 65/268; 65/273 |
Intern'l Class: | C03B 023/025 |
Field of Search: | 65/104,107,268,273,285,106,25.4,182.2 |
3431095 | Mar., 1969 | Ross | 65/107. |
3526489 | Sep., 1970 | McPhail | 65/25. |
4119424 | Oct., 1978 | Comperatore | 65/107. |
4300935 | Nov., 1981 | Seymour | 65/107. |
4356018 | Oct., 1982 | McMaster. | |
4755204 | Jul., 1988 | Boardman et al. | |
4986842 | Jan., 1991 | Peltonen | 65/107. |
Foreign Patent Documents | |||
81329 | Aug., 1987 | FI. |